Draft control for steam-boiler furnaces



Nov. 5, 1929. 1. A. JOHNSON. Er A1.

DRAFT CONTROL FOR STEAM .YBOILER FURNACES Filed March ,5. A19282-,Sheets-Sheet l ooooo I IIIILIIU Illlllb Y, ln/vanto@ :JJUZ 716 071Rhume/14 Nov. 5, 1929. J. A. JOHNSON ET AL Y A DRAFT CONTROL FOR STEAMBOILER FURNACES 2 Sheets-Sheet 2 Filed March 5. 1928 Patented Nov. 5,1929 ure-aire vairs JAMES A. lJOHIN'SO1\T AND GEORGE A. BENSON, OFVIRGIQNIA BEACH, VIlIRGIN'IA,` AS- SIGNORS TO DRAFT-RATER CORPORATION,OF NORFOLK, VIRGINIA, 'A' CORPORA- TION OF VIRGINA DRAFT CONTROL "FORSTEAIVI-BOILERFURNACES Application filed March 3,

rIhis invention relates to draft controlling means for steam boilerfurnaces or like mechanisms, and the general obj ect of the invention isto provide means for reducing the draft either upon a sudden increase inthe draft as, for instance, when fresh coal is thrown upon the fire, orthe reducing of the draft when an excess of steam is being genera-ted,or in other words when the pressure of the steam has risen above apredetermined point.

A further object is to provide for this purpose a draft damper or valveoperating inA connection with a stack, and provide readily adjustablemeans whereby the damper may be held in a normal position at apredetermined distance from the lower end of the stack, the damper beingadjustable to increase or decrease this distance7 and further in thisconnection to provide means tending to resist the initial movement ofthe damper toward the stack or toward the seat but permitting a suddenclosing of the damper.

Still another object is to yprovide means whereby the damper, as beforeremarked, will be shifted toward its seat to reduce or check the draftthrough the stack when steam has been raised beyond a certain pressure,which includes al relief valve, a cylinder into which the relief valveexhausts, the cylinder having a piston operating upon the damper toshift it toward the stack when the piston is subj ected to the pressureof the steam, thus rendering the action of the damper automatic wherethe steam is being produced in excess of requirements.

Other objects will appear in the course of the following description.

Our invention is illustrated in the accompanying drawings, whereinFigure 1 is a front elevation of the smoke box of a steam boiler withthe lfront wall thereof removed, showing our draft regulator applied tothe interior thereof; Y

Figure 2 is a vertical sectional 'view on the .line 2 2 of Figure 1; I

Figure 3 is a fragmentary sectional view showing the draft regulatorapplied to a modified form of flue; I

Figure et is a fragmentary sectional view 1928. Serial No. 258,976.

showing another application of the draft regulator.

Referring to these drawings, 10 designates the smoke box of a waterheater or boiler and 11 Vdesignates the lire tubesl extending 'throughthe boiler 12 and entering the smoke box, the smoke box beingprovidedwith the usual stack 13 extending therefrom. It will be understood thatthe furnace may be of any suitable or usual type and that the embodimentwhich we have illustrated is purely illustrative of one application ofour invention.

Disposed within the smoke box isa cylinder 14thaving therein a float 15.VThis float carries a stenil extending upward through a guide 17 of anysuitable character. At itsA upper end this stem' carries upon it thebellshaped damper 18 which is larger` than the opening into the lstack7through the top of the smoke box. This damperl will never, even atits=highest point,seat' against the 'lower end of the stackY so as tocompletely` cut off the draft but` the dampenmay be shifted into aposition of approximate contact with the lower end of the stack or witha seat inside the stack, as desired, and under these circumstances willcut down orrreduce the draft materially. rEhe damper is retained in anormal position spaced from the lower end of the stack or from its seatby the weight of the damper, the stem or rod 16 and the weight of thefloat 15. l This float is normally supported by a body of water or otherliquid disposed within the cylinder 14 which is maintained at anydesired height by means now to be described. From theA cylinder 14 thereextends a pipe 19 which opens into a cylindrical container 20.

Enteringr into the container is a discharge pipe 21 which is verticallyshiftable through a guidebracket 22 and is held in a shifted position bya set screw 23 or equivalent device.- The upper end ofthis pipe 21is'cony nected by a flexible pipe 24 to the lower end of a tank 25, thistank 25 being a closed tank and having therein a certain amount ofwater. It will be obvious novi7 that thelevel of water Within "thecontainer and, therefore,Y the level of within the cylinder llt willdepend sor upon the adjustment of the pipe 21 and that Athe containerwill be filled up to a point raising or lowering the pipe 21, the heightof Y stem extending upward 'through the top of theV water vwithin thefloat chamber 14.1nay be regulated and this, of course, will regulate .mthe height ofthe float 15 and thev distance of the valve or damper 18from its seat.

Under these circumstances, ifa sudden draft is caused upward through thestack,

such a draft, for instance, as is caused by thev opening of the furnacedoor and the throwing of fresh coal in upon-the lire which causes whatmay be termed a smoke explosion, `the force of the draft rushing outthrough the smoke stack will cause the damper tomove toward the stack,thus reducingthe draft and preventing the escape up the stack of the hotair and other heated products of combustion and the consequent loss ofheating power. A mere slow increase of draft, however, will not causethis' upward movement of the damper as the damperis lheld down by theweight of the damper rod and the float. Y

While the float is supported within the water,- the lower portion of:the float has no Weight but as soon as the float is free from the waterit has'an additional weight tending to check the upward movement ofthedamper. As soon' as the draft has been ref duced below a certain point,of course, the

damper will fall to its initial position which isA governed by theadjustment of the pipe 21, as heretofore stated. v

In order to provide for an automatic movement o-f the damper toward itsclosed position when anV excess of steam is being generated, we' mountupon the damper rod the cross bar 26 or an equivalent element and mountupon the'side of the cylinder 14 bev neath this cross bar a cylinder 27wit-hin which a piston" 28 operates, this piston having ay the cylinderand bearing against the under face of the cross bar 26. The lower end`of the cylinder 27A is connected by means of a pipe 29r to thecasing 80of a relief valve of any usual or suitable type, this-relief valve beingso set by the usual mechanism for this purpose that .it willv pop ofi'or relieve the pressure when the pressure is about five.

pounds below the predetermined pressure re.- quired to operate the usualpop-off valve. This casing 30 is connected by a pipe 31 to thev steamdrum of the engine or to any other suitable chamber having therein steamgenerated by the boiler. 'It will, therefore, be obvious that if anexcess of steam is created and the pressure `increases beyond apredetermined `point that theA relief valve will act, permitting ytheVsteam to pass from the'pipe Thus it will be seen that we have provided Yan automatic draft regulator and an automatic steam regulator'orpressure regulator which will act to impede or reduce draft passingthrough the stove either upon a sudden increasel of draftorvupon anincrease in the steam pressurebeyond a predetermined amount to which therelief valve is set.

In Figure 3, we have illustrated a constructiony operating on exactlythe same principle as heretofore described, except in this case thestack 18A isshown as angular in formwith the iioat chamber 14 disposedbelow the bend of the stack and in axial alignment with the axis of thestack, and in this case the float chamber is disposed not within alsmoke box but below the stack. Otherwise than this it operates inexactly the same manner as the construction first described. i,

In Figure 4, we illustrate another variation of our construction whereina header. 3 is provided into which two stacks 13 open, these stackslleading from separatefurnaces and from which a stack 1311V extends. Thedamper l18 is disposed beneath the lower end of the stack 13b and thestem of this damperY is mounted upon a lever 32, the outer end of ywhich carries the vertical stem or rod 34 which extends downward andconnects to the iioat disposed within theV float chamber 14. It will beseen that this is also a mere variation in the'arrangement of parts anddoes y not .depart from the invention.

While'we have illustrated certain details of construction andarrangement of parts, it is to be understood thatthis is purelyillustrative of the several embodiments shown and to illustrate thegeneral features of the invention and how it may be' applied and that weare notv to be limited to these details except as defined in theappendedclaims.

We claim :-v v

1. In a furnace having a smoke box and a smoke flue extending therefrom,a damper mounted within the smoke box and below the lower end of theflue and adapted to move toward or from the flue, the damper beingmovable toward the flue under the suction created by an increased draftthrough the flue, a vertically disposed rod upon which the damper ismounted, means acting to limit the downward movement of the rod anddamper, said means comprising a oat mounted upon the rod, a liquidchamber in which said Heat is disposed, and manually operable means forincreasing or decreasing the amount of liquid Y i of an increase ofdraft through the Hue to reduce the effective area of the Hue passage,said damper being urged away from this last named position, a liquidchamber, a Hoat therein operatively connected to and movable with thedamper, a barometric tank, a liquid container disposed on a level withthe liquid chamber and communicatively connected thereto at its lowerend, and a pipe entering said container and operatively connected to thetank to take liquid therefrom, the pipe being vertically adjustable tothereby control the level of liquid in the container and in saidchamber.

3. In a furnace having a smoke Hue, a

damper movable under the influence of eXcessive draft to reduce theeffective area of the Hue, a liquid chamber, a Hoat therein operativelyconnected to and movable by and with the damper, the float beingnormally supported by the liquid and supporting the damper.

4. In a furnace having a smoke flue, a damper movable under the inHuenceof eX- cessive draft to reduce the effective area of the Hue, a liquidchamber, a float therein operatively connected to and movable by and jwith the damper, the float being normally supported by the liquid andsupporting the damper, and adjustable means for controlling the heightof liquid in the chamber.

5. In a furnace having a smoke Hue, a damper movable under the inHuenceof eX- cessive draft to restrict the Hue opening, a receptaclecontaining liquid, a member therein and connections between the memberand the damper whereby as the damper moves to restrict the opening ofthe Hue, the member is withdrawn from the liquid and applies its weightas a bias returning the damper to its normal position.

6. In a furnace having a smoke Hue, a damper movable under the inHuenceof excessive draft to restrict the flue opening, a receptacle containingliquid, a member therein and connections between the member and thedamper whereby as the damper moves to restrict the opening of the Hue,the member is withdrawn from the liquid and applies its weight as a biasreturning the damper to its normal position, and adjustable means forcontrolling the liquid level in the receptacle.

7. In a furnace having a smoke Hue, a damper movable under the inHuenceof excessive draft to restrict the flue opening, a receptacle containingliquid, a member therein and connections between the member and thedamper whereby as the damper moves to restrict the opening of the Hue,the member is withdrawn from the liquid and applies its Weight as a biasreturning the damper to its normal position, a barometric tank, a liquidcontainer disposed on a level with the liquid receptacle and connectedtherewith, a pipe

